Intraocular lenses are widely used to be replaced with human opacity crystalline lenses in cataract treatments to compensate the optical powers of the lenses. In intraocular lens insertion surgeries for the cataract treatments, an incision (discission cut) which is several millimeters in length is produced at the edge of the cornea or the sclerocornea, the human crystalline lens is crushed and removed by phacoemulsification and aspiration etc. and the intraocular lens is inserted and fixed in the eye using an intraocular lens insertion apparatus, for example.
Recently, it is considered as desirable to produce an incision with a smaller in size in view of the burden on a patient etc. In addition, it is also desirable to reduce the length of the distal end member of the intraocular lens insertion apparatus inserted through the incision into the eyeball of the patient. Therefore, an indicator showing the insertion length of the intraocular lens insertion apparatus into the eyeball is proposed (See Patent Literature 1).